IR Spectroscopic Features of Gaseous C7H7O+ Ions: Benzylium versus Tropylium Ion Structures
详细信息 查看全文
- 作者：Barbara Chiavarino ; Maria Elisa Crestoni ; Simonetta Fornarini ; Otto Dopfer ; Joel Lemaire ; Philippe Maî ; tre
- 刊名：Journal of Physical Chemistry A
- 出版年：2006
- 出版时间：August 3, 2006
- 年：2006
- 卷：110
- 期：30
- 页码：9352 - 9360
- 全文大小：317K
- 年卷期：v.110,no.30(August 3, 2006)
- ISSN：1520-5215
文摘
Gaseous [C7H7O]+ ions have been formed by protonation of benzaldehyde or tropone (2,4,6-cycloheptatrienone)in the cell of an FT-ICR mass spectrometer using C2H5+ as a Br
nsted acid. The so-formed species havebeen assayed by infrared multiphoton dissociation (IRMPD) using the free electron laser (FEL) at the CLIO(Centre Laser Infrarouge Orsay) facility. The IRMPD features are quite distinct for ions from the two differentprecursors, pointing to two different isomers. A number of potential structures for [C7H7O]+ ions have beenoptimized at the B3LYP/6-31+G(d,p) level of theory, and their relative energies and IR spectra are reported.On this basis, the IRMPD spectra of [C7H7O]+ ions are found to display features characteristic of O-protonatedspecies, with no evidence of any further skeletal rearrangements. The so-formed ions are thus hydroxy-substituted benzylium and tropylium ions, respectively, representative members of the benzylium/tropyliumion family. The IRMPD assay using the FEL laser light has allowed their unambiguous discrimination whereother mass spectrometric techniques have yielded a less conclusive answer.
nsted acid. The so-formed species havebeen assayed by infrared multiphoton dissociation (IRMPD) using the free electron laser (FEL) at the CLIO(Centre Laser Infrarouge Orsay) facility. The IRMPD features are quite distinct for ions from the two differentprecursors, pointing to two different isomers. A number of potential structures for [C7H7O]+ ions have beenoptimized at the B3LYP/6-31+G(d,p) level of theory, and their relative energies and IR spectra are reported.On this basis, the IRMPD spectra of [C7H7O]+ ions are found to display features characteristic of O-protonatedspecies, with no evidence of any further skeletal rearrangements. The so-formed ions are thus hydroxy-substituted benzylium and tropylium ions, respectively, representative members of the benzylium/tropyliumion family. The IRMPD assay using the FEL laser light has allowed their unambiguous discrimination whereother mass spectrometric techniques have yielded a less conclusive answer.